Electronic devices, such as mobiles phones, personal digital assistants (PDAs), cameras, computers, etc., are provided with integrated circuit (IC) chips that perform multiple functions such as computing, voice communication, image and video processing, and storing of information. Nowadays, users prefer compact electronic devices that can support a number of functionalities and have an extended battery life. As a result, there has been a continuous decrease in the size of the IC chips and an increase in the number of functionalities provided by the IC chips. This decrease in the size necessitates a reduction of the level of supply voltage at which the IC chips operate and also reduces power consumption of the IC chips.
A typical IC chip includes a core, an input-output (I/O) ring, and I/O pads. The core includes circuits to perform various functions and also interacts with peripheral circuits through the I/O pads. The core is connected to the I/O pads via the I/O ring. The I/O ring includes multiple I/O cells, which are coupled to the I/O pads. The I/O cells include circuits to provide an interface between the core and the peripheral circuits. Both the core and the I/O ring operate at their respective levels of supply voltage. Generally, the core operates at a level of supply voltage that is lower than that of the I/O ring. However, the I/O ring is usually configured to operate at the same level of supply voltage as the IC chip. If the level of supply voltage at which the IC chip operates is to be changed, the I/O ring becomes obsolete as the I/O ring is configured to operate at a particular supply voltage level only. Thus, the I/O ring has to be re-fabricated for a new level of IC supply voltage.